1. Technical Field
The present disclosure relates to a semiconductor device and to a method of manufacturing the semiconductor device, and more particularly to a semiconductor device having a recess channel and a method of manufacturing the semiconductor device.
2. Description of the Related Art
As semiconductor devices have become more highly integrated, the size of metal oxide semiconductor (MOS) devices have consequently also been reduced. Further, the length of a channel has been reduced up to the degree of deep sub-micron so as to improve the operational speed and current driving performance of the device.
As the length of the channel has been reduced, depletion regions of a source electrode and a drain electrode may be penetrated into the channel, so that the effective length of the channel is reduced. Consequently, a threshold voltage may be reduced, which in turn may cause a short channel effect in which the MOS transistor is deprived of a gate control function. In addition, a punchthrough effect in which dopants in the source and drain electrodes are diffused to the side during the operation of the transistor may also occur.
In particular, as design rules are reduced, a short channel effect is caused. Further, as the amount of implanted ions is increased, leakage current is also increased. Accordingly, it may be difficult to ensure refresh time.
For this reason, there has been proposed a RCAT (Recess Channel Array Transistor). With the RCAT, a recess channel trench is formed in a region, in which the channel of a transistor is formed, so as to ensure a sufficient length of the channel.
FIG. 1 shows a semiconductor device including a common recess channel. In general, dopants for the formation of the channel exist in a channel region. However, in the case of the recess channel shown in FIG. 1, the concentration of the dopants for the formation of the channel is not uniform in the recess channel that is formed so as to correspond to the profile of a recess region r. In other words, a B region positioned at the lower portion of the gate in the recess channel region has a higher concentration of the dopants as compared to A and C regions positioned at the side portions of the gate. As the recess region r is formed and the dopants for the formation of the channel are then implanted, there may be a difficulty in which each of the side regions (A and C regions) has a lower concentration of the dopants as compared to the lower region (B region). Further, as the concentration of the dopants is not uniform in the channel region, there is a possibility that the characteristic and reliability of the device may deteriorate.